Effects of the inclusion of a mixed Psychrotrophic bacteria strain for sewage treatment in constructed wetland in winter seasons

Recent advances and prospects of constructed wetlands in cold climates: a review from 2013 to 2023

Constructed wetland (CW), a promising, environmentally responsible, and effective green ecological treatment technology, is actively involved in the treatment of various forms of wastewater. Low temperatures will, however, lead to issues including plant dormancy, decreased microbial activity, and ice formation in CWs, which will influence how well CWs process wastewater. Applying CWs successfully and continuously in cold areas is extremely difficult. Therefore, it is crucial to find solutions for the pressing issue of increasing the CWs' ability to process wastewater at low temperatures. This review focuses on the effect of cold climate on CWs (plants, substrates, microorganisms, removal effect of pollutants). It meticulously outlines current strategies to enhance CWs' performance under low-temperature conditions, including modifications for the improvement and optimization of the internal components (i.e., plant and substrate selection, bio-augmentation) and enhancement of the external operation conditions of CWs (such as process combination, effluent recirculation, aeration, heat preservation, and operation parameter optimization). Finally, future perspectives on potential research directions and technological innovations that could strengthen CWs' performance in cold climates are prospected. This review aims to contribute valuable insights into the operation strategies, widespread implementation, and subsequent study of CWs in colder climate regions.

New insight for purifying polluted river water using the combination of large-scale rotating biological contactors and integrated constructed wetlands in the cold season

Ecological treatment technologies, applied to deal with polluted river water in the low temperature season, remain limited. In this study, a new insight was put forward for purifying polluted river water using a combination system (CS) of large-scale rotating biological contactors (RBCs) and integrated constructed wetlands in autumn and winter. The treatment performance, average removal contribution (RC), nitrification and denitrification rates, microbial community structure, and ecosystem service value were considered to estimate the combination system. Results revealed that the average removal efficiencies of ammonium (NH₄⁺-N), total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) reached 93.9%, 20.8%, 36.5%, and 37.1%, respectively. The combination system showed excellent removal efficiency of NH₄⁺-N regardless of the effect of low temperature. The maximum values of nitrification and denitrification rates were 59.57 g N/(m³·d) and 0.78 g N/(m²·d), respectively. Considerable differences in bacterial community diversity, richness and relative abundance of functional microbes were observed in the main treatment units, resulting in different average RC to pollutants. The unit capital cost of CS purifying polluted river water was 260 USD/m³ and the operation and maintenance cost was 0.144 million USD/yr. Meanwhile, the ecosystem service value of the CS was 0.334 million USD in autumn and winter. CS not only possessed excellent pollutant purifying efficiencies, but also achieved high ecological service value in the cold season.

Intelligent Measurement and Analysis of Sewage Treatment Parameters based on Fuzzy Neural Algorithm with ARM9 Core CPU

After entering the new century, the state continues to increase the construction of urban sewage treatment projects in response to the deteriorating water pollution situation. How to collect and analyze the sewage parameter variables in the sewage treatment process to ensure the intelligent measurement and accurate operation of the parameters in the treatment application is an urgent problem to be solved. This paper is mainly based on the computer-aided control system built by the ARM9 core embedded chip, and the feasibility and effectiveness of fuzzy neural network algorithms are discussed to improve the intelligent processing of sewage treatment parameters. After analyzing the principle and implementation flow of fuzzy control and neural network, starting from the characteristics of data collected by ARM9 core chip, the hybrid algorithm model is optimized and improved to further improve the convergence speed and accuracy of the algorithm. The simulation experiment proves that the optimized fuzzy neural control algorithm can effectively identify the dissolved oxygen, nitrate nitrogen, and other parameter data in the sewage treatment, and the recognition accuracy is very close to the true precision. Based on biosensors, the ARM9 core chip control system established by a recursive fuzzy neural network can greatly improve the tracking and control ability of parameters such as dissolved oxygen concentration and nitrate nitrogen concentration in microbial degradation. This has a good development prospect in wastewater treatment control applications. The experimental results show that the recursive fuzzy neural network algorithm proposed in this paper can dynamically track and control the nitrate concentration and dissolved oxygen concentration and ensure that the control is within the accuracy range. The accuracy of recognition is very close to the real accuracy.

Purification of Micro-Polluted Lake Water by Biofortification of Vertical Subsurface Flow Constructed Wetlands in Low-Temperature Season

In this study, a novel lab-scale biofortification-combination system (BCS) of Oenanthe javanica and Bacillus series was developed to improve the treatment ability of vertical subsurface flow constructed wetlands (VSFCW) at low temperatures (0–10 °C). The results showed that BCS-VSFCW overcame the adverse effects of low temperature and achieved the deep removal of nutrients. In addition, the removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) by BCS-VSFCW were 38.65%, 28.20%, 18.82%, and 14.57% higher than those of blank control, respectively. During the experiment, Oenanthe javanica and low temperature tolerant Bacillus complemented each other in terms of microbial activity and plant uptake. Therefore, VSFCW combined with Oenanthe javanica and low temperature tolerant Bacillus has a promising future in low temperature (<10 °C) areas of northern China.

Critically important antimicrobial resistant Enterobacteriaceae in Irish farm effluent and their removal in integrated constructed wetlands

This study investigated the ability of Integrated Constructed Wetlands (ICWs) to remove critically important antimicrobial resistant organisms (AROs) from farm wastewater. Influent samples from the untreated farm waste and effluent samples taken at the end of the ICW system were collected monthly from four ICWs, serving four different farm types (suckler, dairy, dairy & poultry and pig). Using selective media to screen for the presence of carbapenemase resistant organisms, plasmid mediated and AmpC β-Lactamase producing organisms (ESBL/pAmpC) and fluoroquinolone resistant organisms, a total of 82 AROs were obtained with the majority being E. coli (n = 79). Statistically significant were the differences on the number of AROs isolated from influent (higher) compared to effluent, as well as a seasonal effect, with less AROs recovered during winter in comparison to other seasons (P < 0.05). On the other hand, there was no significant differences in the recovery of AROs on different farms. The majority of isolates from each of the farms (99%) were multi drug resistant, with 65% resistant to seven or more antimicrobials. A high incidence of tetracycline, trimethoprim/sulfamethoxazole, and ampicillin resistance was common to the isolates from all four farms but there were differences in ESBL levels with 63% of the isolates recovered from Farm 4 (piggery) being ESBLs compared to 18%, 36% and 4.5% recovered from Farms 1 (suckler), 2 (dairy) and 3 (dairy & poultry), respectively. No carbapenemase producing organisms were isolated. Our results showed that ICWs are effective in removing critically important AROs from farm wastewater on all four farm types.

How to enhance the purification performance of traditional floating treatment wetlands (FTWs) at low temperatures: Strengthening strategies

Pollution of freshwaters poses a major threat to water quality and human health and thus, nutrients have been targeted for mitigation. One such control measure is floating treatment wetlands (FTWs), which are designed to employ vigorous macrophytes above the water surface and extensive plant root system below the water surface to increase plant uptake of nutrients. The efficacy of FTWs in purifying different water systems has been widely studied and reviewed, but most studies have been performed in warm periods when FTW macrophytes are actively growing. In low-temperature conditions, the metabolic processes of macrophytes and microbial activity are usually weakened or reduced by the winter months and are not actively assimilating pollutants. These circumstances hamper the purification ability of FTWs to perform as designed. Furthermore, decayed macrophytes could release pollutants into the water column. Hence, this paper aimed to systematically summarize strategies for use of enhanced FTWs in eutrophic water improvement at low temperature and identify future directions to be addressed in intensifying FTW performance in low-temperature conditions. Low-temperature FTW show variable nutrient removal efficiencies ranging from 22% to 98%. Current amendments to enhance FTW purification performance, ranging from direct strategies for internal components to indirect enhancement of external operation environments encourage the FTW efficacy to some extent. However, the sustainability and sufficiency of water purification efficiency remain a great challenge. Keeping in mind the need for optimizing the FTW components and dealing with high organic and inorganic chemicals, future research should be carried out at the large field-scale and focus on macrophyte- benthos- microorganism synergistic enhancement, breeding of cold-tolerant macrophytes, and combination of FTWs with many strategies, as well as rational design and operational approaches under cold conditions.